April 20, 2014

HAVANA — The imposing, seven-story structure with darkened windows sits just across from the Malecon, or sea wall, central Havana’s communal hangout. It is unadorned, flying no flags, offering few signs that germinating inside are seeds of a better relationship between official enemies.

The United States cut off relations and imposed a trade embargo with communist Cuba more than half a century ago. But at the so-called US Interests Section in Havana, 50 US diplomats and 300 locally hired Cubans are quietly working on a range of common challenges...